Brand new factory sealed no-frills dvd is the fourth in the franchise.

At the begining of the film, we get a glimpse into the future. A war has been raging between mutants and the governments that want to destroy them. A group of advanced robots called Sentinels hunt mutants, destroy them, and are rapidly eliminating the population. Professor X and his X-Men are almost all gone, barely escaping each attempted assassination. Their last chance at ending the war may be to go back in time and keep it from ever starting.

So Kitty Pride sends Wolverine back to the '70s where he must stop Mystique from killling Trask, inventor of the Sentinels, an event that sets the stage for the evolution of the Sentinels and the ultimate annhilation of the mutants. In order to stop her, Logan must enlist the help of two old friends:

The young Professor and his arch enemy Magneto. Unfortunately, neither of the two men are in a position to help and will both need convincing in order to set aside their differences, band together, and change the future once and for all.